From: Bryan Quigley <bryan.quigley@canonical.com>
Date: Sat, 2 Nov 2019 21:06:44 -0700
Subject: Python3 port of ndiff

Ported all python scrips in ndiff/ except setup.py

Some hints on cmp taken from #1484

Minor tweaks to Makefile to support python3, but unsure if
there is a better way to do that.

Seperated .travis.yml commands for easier debugging where it breaks.

This closes the easy half of #1176

Resolves: #1484
---
 .travis.yml                   |   8 +-
 Makefile.in                   |   6 +-
 ndiff/ndiff.py                | 503 +++++++++++++++++++++---------------------
 ndiff/ndifftest.py            |  94 ++++----
 ndiff/scripts/ndiff           |  14 +-
 ndiff/setup.py                |  44 ++--
 ndiff/test-scans/anonymize.py |  18 +-
 7 files changed, 346 insertions(+), 341 deletions(-)
 mode change 100644 => 100755 ndiff/setup.py

--- a/.travis.yml
+++ b/.travis.yml
@@ -4,7 +4,13 @@ compiler:
   - clang
 # Change this to your needs
 sudo: false
-script: mkdir /tmp/n && ./configure $SSL_FLAG $LUA_FLAG --prefix=/tmp/n && make && make check && make install && /tmp/n/bin/nmap -A localhost
+script:
+  - "mkdir /tmp/n"
+  - "./configure $SSL_FLAG $LUA_FLAG --prefix=/tmp/n"
+  - "make"
+  - "make check"
+  - "make install"
+  - "/tmp/n/bin/nmap -A localhost"
 
 env:
   - SSL_FLAG="--without-openssl" LUA_FLAG="--without-liblua"
--- a/Makefile.in
+++ b/Makefile.in
@@ -34,6 +34,7 @@ ZENMAPDIR = @ZENMAPDIR@
 NDIFFDIR = @NDIFFDIR@
 NPINGDIR = @NPINGDIR@
 PYTHON = @PYTHON@
+PYTHON3 = /usr/bin/env python3
 DEFS = @DEFS@ -DNMAP_PLATFORM=\"$(NMAP_PLATFORM)\" -DNMAPDATADIR=\"$(nmapdatadir)\"
 # With GCC, add extra security checks to source code.
 # http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
@@ -361,6 +362,7 @@ tests/check_dns: $(OBJS)
 # this as the location of the interpreter whenever we're not doing a
 # local installation.
 DEFAULT_PYTHON_PATH = /usr/bin/env python
+DEFAULT_PYTHON3_PATH = /usr/bin/env python3
 
 build-zenmap: $(ZENMAPDIR)/setup.py $(ZENMAPDIR)/zenmapCore/Version.py
 # When DESTDIR is defined, assume we're building an executable
@@ -381,7 +383,7 @@ install-zenmap: $(ZENMAPDIR)/setup.py
 	ln -sf zenmap $(DESTDIR)$(bindir)/xnmap
 
 build-ndiff:
-	cd $(NDIFFDIR) && $(PYTHON) setup.py build $(if $(DESTDIR),--executable "$(DEFAULT_PYTHON_PATH)")
+	cd $(NDIFFDIR) && $(PYTHON) setup.py build $(if $(DESTDIR),--executable "$(DEFAULT_PYTHON3_PATH)")
 
 build-nping: $(NPINGDIR)/Makefile build-nbase build-nsock build-netutil $(NPINGDIR)/nping.h @DNET_BUILD@ @PCAP_BUILD@
 	@cd $(NPINGDIR) && $(MAKE)
@@ -451,7 +453,7 @@ check-ncat:
 	@cd $(NCATDIR) && $(MAKE) check
 
 check-ndiff:
-	@cd $(NDIFFDIR) && $(PYTHON) ndifftest.py
+	@cd $(NDIFFDIR) && $(PYTHON3) ndifftest.py
 
 check-nsock:
 	@cd $(NSOCKDIR)/src && $(MAKE) check
--- a/ndiff/ndiff.py
+++ b/ndiff/ndiff.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Ndiff
 #
@@ -25,11 +25,11 @@ xml.__path__ = [x for x in xml.__path__
 import xml.sax
 import xml.sax.saxutils
 import xml.dom.minidom
-from StringIO import StringIO
+from io import StringIO
 
 verbose = False
 
-NDIFF_XML_VERSION = u"1"
+NDIFF_XML_VERSION = "1"
 
 
 class OverrideEntityResolver(xml.sax.handler.EntityResolver):
@@ -74,35 +74,35 @@ class Scan(object):
     def write_nmaprun_open(self, writer):
         attrs = {}
         if self.scanner is not None:
-            attrs[u"scanner"] = self.scanner
+            attrs["scanner"] = self.scanner
         if self.args is not None:
-            attrs[u"args"] = self.args
+            attrs["args"] = self.args
         if self.start_date is not None:
-            attrs[u"start"] = "%d" % time.mktime(self.start_date.timetuple())
-            attrs[u"startstr"] = self.start_date.strftime(
+            attrs["start"] = "%d" % time.mktime(self.start_date.timetuple())
+            attrs["startstr"] = self.start_date.strftime(
                     "%a %b %d %H:%M:%S %Y")
         if self.version is not None:
-            attrs[u"version"] = self.version
-        writer.startElement(u"nmaprun", attrs)
+            attrs["version"] = self.version
+        writer.startElement("nmaprun", attrs)
 
     def write_nmaprun_close(self, writer):
-        writer.endElement(u"nmaprun")
+        writer.endElement("nmaprun")
 
     def nmaprun_to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
-        elem = document.createElement(u"nmaprun")
+        elem = document.createElement("nmaprun")
         if self.scanner is not None:
-            elem.setAttribute(u"scanner", self.scanner)
+            elem.setAttribute("scanner", self.scanner)
         if self.args is not None:
-            elem.setAttribute(u"args", self.args)
+            elem.setAttribute("args", self.args)
         if self.start_date is not None:
             elem.setAttribute(
-                    u"start", "%d" % time.mktime(self.start_date.timetuple()))
+                    "start", "%d" % time.mktime(self.start_date.timetuple()))
             elem.setAttribute(
-                    u"startstr",
+                    "startstr",
                     self.start_date.strftime("%a %b %d %H:%M:%S %Y"))
         if self.version is not None:
-            elem.setAttribute(u"version", self.version)
+            elem.setAttribute("version", self.version)
         frag.appendChild(elem)
         return frag
 
@@ -132,17 +132,17 @@ class Host(object):
 
     def format_name(self):
         """Return a human-readable identifier for this host."""
-        address_s = u", ".join(a.s for a in sorted(self.addresses))
-        hostname_s = u", ".join(sorted(self.hostnames))
+        address_s = ", ".join(a.s for a in sorted(self.addresses))
+        hostname_s = ", ".join(sorted(self.hostnames))
         if len(hostname_s) > 0:
             if len(address_s) > 0:
-                return u"%s (%s)" % (hostname_s, address_s)
+                return "%s (%s)" % (hostname_s, address_s)
             else:
                 return hostname_s
         elif len(address_s) > 0:
             return address_s
         else:
-            return u"<no name>"
+            return "<no name>"
 
     def add_port(self, port):
         self.ports[port.spec] = port
@@ -159,46 +159,46 @@ class Host(object):
         return state is None or state in self.extraports
 
     def extraports_string(self):
-        list = [(count, state) for (state, count) in self.extraports.items()]
+        locallist = [(count, state) for (state, count) in list(self.extraports.items())]
         # Reverse-sort by count.
-        list.sort(reverse=True)
-        return u", ".join(
-                [u"%d %s ports" % (count, state) for (count, state) in list])
+        locallist.sort(reverse=True)
+        return ", ".join(
+                ["%d %s ports" % (count, state) for (count, state) in locallist])
 
     def state_to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
         if self.state is not None:
-            elem = document.createElement(u"status")
-            elem.setAttribute(u"state", self.state)
+            elem = document.createElement("status")
+            elem.setAttribute("state", self.state)
             frag.appendChild(elem)
         return frag
 
     def hostname_to_dom_fragment(self, document, hostname):
         frag = document.createDocumentFragment()
-        elem = document.createElement(u"hostname")
-        elem.setAttribute(u"name", hostname)
+        elem = document.createElement("hostname")
+        elem.setAttribute("name", hostname)
         frag.appendChild(elem)
         return frag
 
     def extraports_to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
-        for state, count in self.extraports.items():
-            elem = document.createElement(u"extraports")
-            elem.setAttribute(u"state", state)
-            elem.setAttribute(u"count", unicode(count))
+        for state, count in list(self.extraports.items()):
+            elem = document.createElement("extraports")
+            elem.setAttribute("state", state)
+            elem.setAttribute("count", str(count))
             frag.appendChild(elem)
         return frag
 
     def os_to_dom_fragment(self, document, os):
         frag = document.createDocumentFragment()
-        elem = document.createElement(u"osmatch")
-        elem.setAttribute(u"name", os)
+        elem = document.createElement("osmatch")
+        elem.setAttribute("name", os)
         frag.appendChild(elem)
         return frag
 
     def to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
-        elem = document.createElement(u"host")
+        elem = document.createElement("host")
 
         if self.state is not None:
             elem.appendChild(self.state_to_dom_fragment(document))
@@ -207,13 +207,13 @@ class Host(object):
             elem.appendChild(addr.to_dom_fragment(document))
 
         if len(self.hostnames) > 0:
-            hostnames_elem = document.createElement(u"hostnames")
+            hostnames_elem = document.createElement("hostnames")
             for hostname in self.hostnames:
                 hostnames_elem.appendChild(
                         self.hostname_to_dom_fragment(document, hostname))
             elem.appendChild(hostnames_elem)
 
-        ports_elem = document.createElement(u"ports")
+        ports_elem = document.createElement("ports")
         ports_elem.appendChild(self.extraports_to_dom_fragment(document))
         for port in sorted(self.ports.values()):
             if not self.is_extraports(port.state):
@@ -222,13 +222,13 @@ class Host(object):
             elem.appendChild(ports_elem)
 
         if len(self.os) > 0:
-            os_elem = document.createElement(u"os")
+            os_elem = document.createElement("os")
             for os in self.os:
                 os_elem.appendChild(self.os_to_dom_fragment(document, os))
             elem.appendChild(os_elem)
 
         if len(self.script_results) > 0:
-            hostscript_elem = document.createElement(u"hostscript")
+            hostscript_elem = document.createElement("hostscript")
             for sr in self.script_results:
                 hostscript_elem.appendChild(sr.to_dom_fragment(document))
             elem.appendChild(hostscript_elem)
@@ -242,7 +242,7 @@ class Address(object):
         self.s = s
 
     def __eq__(self, other):
-        return self.__cmp__(other) == 0
+        return self.sort_key() == other.sort_key()
 
     def __ne__(self, other):
         return not self.__eq__(other)
@@ -250,8 +250,8 @@ class Address(object):
     def __hash__(self):
         return hash(self.sort_key())
 
-    def __cmp__(self, other):
-        return cmp(self.sort_key(), other.sort_key())
+    def __lt__(self, other):
+        return self.sort_key() < other.sort_key()
 
     def __str__(self):
         return str(self.s)
@@ -260,21 +260,21 @@ class Address(object):
         return self.s
 
     def new(type, s):
-        if type == u"ipv4":
+        if type == "ipv4":
             return IPv4Address(s)
-        elif type == u"ipv6":
+        elif type == "ipv6":
             return IPv6Address(s)
-        elif type == u"mac":
+        elif type == "mac":
             return MACAddress(s)
         else:
-            raise ValueError(u"Unknown address type %s." % type)
+            raise ValueError("Unknown address type %s." % type)
     new = staticmethod(new)
 
     def to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
-        elem = document.createElement(u"address")
-        elem.setAttribute(u"addr", self.s)
-        elem.setAttribute(u"addrtype", self.type)
+        elem = document.createElement("address")
+        elem.setAttribute("addr", self.s)
+        elem.setAttribute("addrtype", self.type)
         frag.appendChild(elem)
         return frag
 
@@ -283,21 +283,21 @@ class Address(object):
 
 
 class IPv4Address(Address):
-    type = property(lambda self: u"ipv4")
+    type = property(lambda self: "ipv4")
 
     def sort_key(self):
         return (0, self.s)
 
 
 class IPv6Address(Address):
-    type = property(lambda self: u"ipv6")
+    type = property(lambda self: "ipv6")
 
     def sort_key(self):
         return (1, self.s)
 
 
 class MACAddress(Address):
-    type = property(lambda self: u"mac")
+    type = property(lambda self: "mac")
 
     def sort_key(self):
         return (2, self.s)
@@ -316,31 +316,28 @@ class Port(object):
 
     def state_string(self):
         if self.state is None:
-            return u"unknown"
+            return "unknown"
         else:
-            return unicode(self.state)
+            return str(self.state)
 
     def spec_string(self):
-        return u"%d/%s" % self.spec
+        return "%d/%s" % self.spec
 
     def __hash__(self):
         return hash(self.spec)
 
-    def __cmp__(self, other):
-        d = cmp(self.spec, other.spec)
-        if d != 0:
-            return d
-        return cmp((self.spec, self.service, self.script_results),
-            (other.spec, other.service, other.script_results))
+    def __lt__(self, other):
+        return (self.spec, self.service, self.script_results) < (
+            other.spec, other.service, other.script_results)
 
     def to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
-        elem = document.createElement(u"port")
-        elem.setAttribute(u"portid", unicode(self.spec[0]))
-        elem.setAttribute(u"protocol", self.spec[1])
+        elem = document.createElement("port")
+        elem.setAttribute("portid", str(self.spec[0]))
+        elem.setAttribute("protocol", self.spec[1])
         if self.state is not None:
-            state_elem = document.createElement(u"state")
-            state_elem.setAttribute(u"state", self.state)
+            state_elem = document.createElement("state")
+            state_elem.setAttribute("state", self.state)
             elem.appendChild(state_elem)
         elem.appendChild(self.service.to_dom_fragment(document))
         for sr in self.script_results:
@@ -384,7 +381,7 @@ class Service(object):
         if len(parts) == 0:
             return None
         else:
-            return u"/".join(parts)
+            return "/".join(parts)
 
     def version_string(self):
         """Get a string like in the VERSION column of Nmap output."""
@@ -394,17 +391,17 @@ class Service(object):
         if self.version is not None:
             parts.append(self.version)
         if self.extrainfo is not None:
-            parts.append(u"(%s)" % self.extrainfo)
+            parts.append("(%s)" % self.extrainfo)
 
         if len(parts) == 0:
             return None
         else:
-            return u" ".join(parts)
+            return " ".join(parts)
 
     def to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
-        elem = document.createElement(u"service")
-        for attr in (u"name", u"product", u"version", u"extrainfo", u"tunnel"):
+        elem = document.createElement("service")
+        for attr in ("name", "product", "version", "extrainfo", "tunnel"):
             v = getattr(self, attr)
             if v is None:
                 continue
@@ -434,53 +431,53 @@ class ScriptResult(object):
         result = []
         lines = self.output.splitlines()
         if len(lines) > 0:
-            lines[0] = self.id + u": " + lines[0]
+            lines[0] = self.id + ": " + lines[0]
         for line in lines[:-1]:
-            result.append(u"|  " + line)
+            result.append("|  " + line)
         if len(lines) > 0:
-            result.append(u"|_ " + lines[-1])
+            result.append("|_ " + lines[-1])
         return result
 
     def to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
-        elem = document.createElement(u"script")
-        elem.setAttribute(u"id", self.id)
-        elem.setAttribute(u"output", self.output)
+        elem = document.createElement("script")
+        elem.setAttribute("id", self.id)
+        elem.setAttribute("output", self.output)
         frag.appendChild(elem)
         return frag
 
 
 def format_banner(scan):
     """Format a startup banner more or less like Nmap does."""
-    scanner = u"Nmap"
-    if scan.scanner is not None and scan.scanner != u"nmap":
+    scanner = "Nmap"
+    if scan.scanner is not None and scan.scanner != "nmap":
         scanner = scan.scanner
     parts = [scanner]
     if scan.version is not None:
         parts.append(scan.version)
-    parts.append(u"scan")
+    parts.append("scan")
     if scan.start_date is not None:
-        parts.append(u"initiated %s" % scan.start_date.strftime(
+        parts.append("initiated %s" % scan.start_date.strftime(
             "%a %b %d %H:%M:%S %Y"))
     if scan.args is not None:
-        parts.append(u"as: %s" % scan.args)
-    return u" ".join(parts)
+        parts.append("as: %s" % scan.args)
+    return " ".join(parts)
 
 
 def print_script_result_diffs_text(title, script_results_a, script_results_b,
         script_result_diffs, f=sys.stdout):
-    table = Table(u"*")
+    table = Table("*")
     for sr_diff in script_result_diffs:
         sr_diff.append_to_port_table(table)
     if len(table) > 0:
-        print >> f
+        print(file=f)
         if len(script_results_b) == 0:
-            print >> f, u"-%s:" % title
+            print("-%s:" % title, file=f)
         elif len(script_results_a) == 0:
-            print >> f, u"+%s:" % title
+            print("+%s:" % title, file=f)
         else:
-            print >> f, u" %s:" % title
-        print >> f, table
+            print(" %s:" % title, file=f)
+        print(table, file=f)
 
 
 def script_result_diffs_to_dom_fragment(elem, script_results_a,
@@ -488,13 +485,13 @@ def script_result_diffs_to_dom_fragment(
     if len(script_results_a) == 0 and len(script_results_b) == 0:
         return document.createDocumentFragment()
     elif len(script_results_b) == 0:
-        a_elem = document.createElement(u"a")
+        a_elem = document.createElement("a")
         for sr in script_results_a:
             elem.appendChild(sr.to_dom_fragment(document))
         a_elem.appendChild(elem)
         return a_elem
     elif len(script_results_a) == 0:
-        b_elem = document.createElement(u"b")
+        b_elem = document.createElement("b")
         for sr in script_results_b:
             elem.appendChild(sr.to_dom_fragment(document))
         b_elem.appendChild(elem)
@@ -579,10 +576,10 @@ class ScanDiffText(ScanDiff):
         banner_a = format_banner(self.scan_a)
         banner_b = format_banner(self.scan_b)
         if banner_a != banner_b:
-            print >> self.f, u"-%s" % banner_a
-            print >> self.f, u"+%s" % banner_b
+            print("-%s" % banner_a, file=self.f)
+            print("+%s" % banner_b, file=self.f)
         elif verbose:
-            print >> self.f, u" %s" % banner_a
+            print(" %s" % banner_a, file=self.f)
 
     def output_pre_scripts(self, pre_script_result_diffs):
         print_script_result_diffs_text("Pre-scan script results",
@@ -595,7 +592,7 @@ class ScanDiffText(ScanDiff):
             post_script_result_diffs, self.f)
 
     def output_host_diff(self, h_diff):
-        print >> self.f
+        print(file=self.f)
         h_diff.print_text(self.f)
 
     def output_ending(self):
@@ -620,8 +617,8 @@ class ScanDiffXML(ScanDiff):
 
     def output_beginning(self):
         self.writer.startDocument()
-        self.writer.startElement(u"nmapdiff", {u"version": NDIFF_XML_VERSION})
-        self.writer.startElement(u"scandiff", {})
+        self.writer.startElement("nmapdiff", {"version": NDIFF_XML_VERSION})
+        self.writer.startElement("scandiff", {})
 
         if self.nmaprun_differs():
             self.writer.frag_a(
@@ -634,7 +631,7 @@ class ScanDiffXML(ScanDiff):
 
     def output_pre_scripts(self, pre_script_result_diffs):
         if len(pre_script_result_diffs) > 0 or verbose:
-            prescript_elem = self.document.createElement(u"prescript")
+            prescript_elem = self.document.createElement("prescript")
             frag = script_result_diffs_to_dom_fragment(
                 prescript_elem, self.scan_a.pre_script_results,
                 self.scan_b.pre_script_results, pre_script_result_diffs,
@@ -644,7 +641,7 @@ class ScanDiffXML(ScanDiff):
 
     def output_post_scripts(self, post_script_result_diffs):
         if len(post_script_result_diffs) > 0 or verbose:
-            postscript_elem = self.document.createElement(u"postscript")
+            postscript_elem = self.document.createElement("postscript")
             frag = script_result_diffs_to_dom_fragment(
                 postscript_elem, self.scan_a.post_script_results,
                 self.scan_b.post_script_results, post_script_result_diffs,
@@ -658,8 +655,8 @@ class ScanDiffXML(ScanDiff):
         frag.unlink()
 
     def output_ending(self):
-        self.writer.endElement(u"scandiff")
-        self.writer.endElement(u"nmapdiff")
+        self.writer.endElement("scandiff")
+        self.writer.endElement("nmapdiff")
         self.writer.endDocument()
 
 
@@ -717,9 +714,9 @@ class HostDiff(object):
         self.cost += os_cost
 
         extraports_a = tuple((count, state)
-                for (state, count) in self.host_a.extraports.items())
+                for (state, count) in list(self.host_a.extraports.items()))
         extraports_b = tuple((count, state)
-                for (state, count) in self.host_b.extraports.items())
+                for (state, count) in list(self.host_b.extraports.items()))
         if extraports_a != extraports_b:
             self.extraports_changed = True
             self.cost += 1
@@ -745,69 +742,69 @@ class HostDiff(object):
         # Names and addresses.
         if self.id_changed:
             if host_a.state is not None:
-                print >> f, u"-%s:" % host_a.format_name()
+                print("-%s:" % host_a.format_name(), file=f)
             if self.host_b.state is not None:
-                print >> f, u"+%s:" % host_b.format_name()
+                print("+%s:" % host_b.format_name(), file=f)
         else:
-            print >> f, u" %s:" % host_a.format_name()
+            print(" %s:" % host_a.format_name(), file=f)
 
         # State.
         if self.state_changed:
             if host_a.state is not None:
-                print >> f, u"-Host is %s." % host_a.state
+                print("-Host is %s." % host_a.state, file=f)
             if host_b.state is not None:
-                print >> f, u"+Host is %s." % host_b.state
+                print("+Host is %s." % host_b.state, file=f)
         elif verbose:
-            print >> f, u" Host is %s." % host_b.state
+            print(" Host is %s." % host_b.state, file=f)
 
         # Extraports.
         if self.extraports_changed:
             if len(host_a.extraports) > 0:
-                print >> f, u"-Not shown: %s" % host_a.extraports_string()
+                print("-Not shown: %s" % host_a.extraports_string(), file=f)
             if len(host_b.extraports) > 0:
-                print >> f, u"+Not shown: %s" % host_b.extraports_string()
+                print("+Not shown: %s" % host_b.extraports_string(), file=f)
         elif verbose:
             if len(host_a.extraports) > 0:
-                print >> f, u" Not shown: %s" % host_a.extraports_string()
+                print(" Not shown: %s" % host_a.extraports_string(), file=f)
 
         # Port table.
-        port_table = Table(u"** * * *")
+        port_table = Table("** * * *")
         if host_a.state is None:
-            mark = u"+"
+            mark = "+"
         elif host_b.state is None:
-            mark = u"-"
+            mark = "-"
         else:
-            mark = u" "
-        port_table.append((mark, u"PORT", u"STATE", u"SERVICE", u"VERSION"))
+            mark = " "
+        port_table.append((mark, "PORT", "STATE", "SERVICE", "VERSION"))
 
         for port in self.ports:
             port_diff = self.port_diffs[port]
             port_diff.append_to_port_table(port_table, host_a, host_b)
 
         if len(port_table) > 1:
-            print >> f, port_table
+            print(port_table, file=f)
 
         # OS changes.
         if self.os_changed or verbose:
             if len(host_a.os) > 0:
                 if len(host_b.os) > 0:
-                    print >> f, u" OS details:"
+                    print(" OS details:", file=f)
                 else:
-                    print >> f, u"-OS details:"
+                    print("-OS details:", file=f)
             elif len(host_b.os) > 0:
-                print >> f, u"+OS details:"
+                print("+OS details:", file=f)
             # os_diffs is a list of 5-tuples returned by
             # difflib.SequenceMatcher.
             for op, i1, i2, j1, j2 in self.os_diffs:
                 if op == "replace" or op == "delete":
                     for i in range(i1, i2):
-                        print >> f, "-  %s" % host_a.os[i]
+                        print("-  %s" % host_a.os[i], file=f)
                 if op == "replace" or op == "insert":
                     for i in range(j1, j2):
-                        print >> f, "+  %s" % host_b.os[i]
+                        print("+  %s" % host_b.os[i], file=f)
                 if op == "equal":
                     for i in range(i1, i2):
-                        print >> f, "   %s" % host_a.os[i]
+                        print("   %s" % host_a.os[i], file=f)
 
         print_script_result_diffs_text("Host script results",
             host_a.script_results, host_b.script_results,
@@ -818,32 +815,32 @@ class HostDiff(object):
         host_b = self.host_b
 
         frag = document.createDocumentFragment()
-        hostdiff_elem = document.createElement(u"hostdiff")
+        hostdiff_elem = document.createElement("hostdiff")
         frag.appendChild(hostdiff_elem)
 
         if host_a.state is None or host_b.state is None:
             # The host is missing in one scan. Output the whole thing.
             if host_a.state is not None:
-                a_elem = document.createElement(u"a")
+                a_elem = document.createElement("a")
                 a_elem.appendChild(host_a.to_dom_fragment(document))
                 hostdiff_elem.appendChild(a_elem)
             elif host_b.state is not None:
-                b_elem = document.createElement(u"b")
+                b_elem = document.createElement("b")
                 b_elem.appendChild(host_b.to_dom_fragment(document))
                 hostdiff_elem.appendChild(b_elem)
             return frag
 
-        host_elem = document.createElement(u"host")
+        host_elem = document.createElement("host")
 
         # State.
         if host_a.state == host_b.state:
             if verbose:
                 host_elem.appendChild(host_a.state_to_dom_fragment(document))
         else:
-            a_elem = document.createElement(u"a")
+            a_elem = document.createElement("a")
             a_elem.appendChild(host_a.state_to_dom_fragment(document))
             host_elem.appendChild(a_elem)
-            b_elem = document.createElement(u"b")
+            b_elem = document.createElement("b")
             b_elem.appendChild(host_b.state_to_dom_fragment(document))
             host_elem.appendChild(b_elem)
 
@@ -852,31 +849,31 @@ class HostDiff(object):
         addrset_b = set(host_b.addresses)
         for addr in sorted(addrset_a.intersection(addrset_b)):
             host_elem.appendChild(addr.to_dom_fragment(document))
-        a_elem = document.createElement(u"a")
+        a_elem = document.createElement("a")
         for addr in sorted(addrset_a - addrset_b):
             a_elem.appendChild(addr.to_dom_fragment(document))
         if a_elem.hasChildNodes():
             host_elem.appendChild(a_elem)
-        b_elem = document.createElement(u"b")
+        b_elem = document.createElement("b")
         for addr in sorted(addrset_b - addrset_a):
             b_elem.appendChild(addr.to_dom_fragment(document))
         if b_elem.hasChildNodes():
             host_elem.appendChild(b_elem)
 
         # Host names.
-        hostnames_elem = document.createElement(u"hostnames")
+        hostnames_elem = document.createElement("hostnames")
         hostnameset_a = set(host_a.hostnames)
         hostnameset_b = set(host_b.hostnames)
         for hostname in sorted(hostnameset_a.intersection(hostnameset_b)):
             hostnames_elem.appendChild(
                     host_a.hostname_to_dom_fragment(document, hostname))
-        a_elem = document.createElement(u"a")
+        a_elem = document.createElement("a")
         for hostname in sorted(hostnameset_a - hostnameset_b):
             a_elem.appendChild(
                     host_a.hostname_to_dom_fragment(document, hostname))
         if a_elem.hasChildNodes():
             hostnames_elem.appendChild(a_elem)
-        b_elem = document.createElement(u"b")
+        b_elem = document.createElement("b")
         for hostname in sorted(hostnameset_b - hostnameset_a):
             b_elem.appendChild(
                     host_b.hostname_to_dom_fragment(document, hostname))
@@ -885,15 +882,15 @@ class HostDiff(object):
         if hostnames_elem.hasChildNodes():
             host_elem.appendChild(hostnames_elem)
 
-        ports_elem = document.createElement(u"ports")
+        ports_elem = document.createElement("ports")
         # Extraports.
         if host_a.extraports == host_b.extraports:
             ports_elem.appendChild(host_a.extraports_to_dom_fragment(document))
         else:
-            a_elem = document.createElement(u"a")
+            a_elem = document.createElement("a")
             a_elem.appendChild(host_a.extraports_to_dom_fragment(document))
             ports_elem.appendChild(a_elem)
-            b_elem = document.createElement(u"b")
+            b_elem = document.createElement("b")
             b_elem.appendChild(host_b.extraports_to_dom_fragment(document))
             ports_elem.appendChild(b_elem)
         # Port list.
@@ -909,18 +906,18 @@ class HostDiff(object):
 
         # OS changes.
         if self.os_changed or verbose:
-            os_elem = document.createElement(u"os")
+            os_elem = document.createElement("os")
             # os_diffs is a list of 5-tuples returned by
             # difflib.SequenceMatcher.
             for op, i1, i2, j1, j2 in self.os_diffs:
                 if op == "replace" or op == "delete":
-                    a_elem = document.createElement(u"a")
+                    a_elem = document.createElement("a")
                     for i in range(i1, i2):
                         a_elem.appendChild(host_a.os_to_dom_fragment(
                             document, host_a.os[i]))
                     os_elem.appendChild(a_elem)
                 if op == "replace" or op == "insert":
-                    b_elem = document.createElement(u"b")
+                    b_elem = document.createElement("b")
                     for i in range(j1, j2):
                         b_elem.appendChild(host_b.os_to_dom_fragment(
                             document, host_b.os[i]))
@@ -934,7 +931,7 @@ class HostDiff(object):
 
         # Host script changes.
         if len(self.script_result_diffs) > 0 or verbose:
-            hostscript_elem = document.createElement(u"hostscript")
+            hostscript_elem = document.createElement("hostscript")
             host_elem.appendChild(script_result_diffs_to_dom_fragment(
                 hostscript_elem, host_a.script_results,
                 host_b.script_results, self.script_result_diffs,
@@ -987,38 +984,38 @@ class PortDiff(object):
             self.port_b.service.version_string()]
         if a_columns == b_columns:
             if verbose or self.script_result_diffs > 0:
-                table.append([u" "] + a_columns)
+                table.append([" "] + a_columns)
         else:
             if not host_a.is_extraports(self.port_a.state):
-                table.append([u"-"] + a_columns)
+                table.append(["-"] + a_columns)
             if not host_b.is_extraports(self.port_b.state):
-                table.append([u"+"] + b_columns)
+                table.append(["+"] + b_columns)
 
         for sr_diff in self.script_result_diffs:
             sr_diff.append_to_port_table(table)
 
     def to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
-        portdiff_elem = document.createElement(u"portdiff")
+        portdiff_elem = document.createElement("portdiff")
         frag.appendChild(portdiff_elem)
         if (self.port_a.spec == self.port_b.spec and
                 self.port_a.state == self.port_b.state):
-            port_elem = document.createElement(u"port")
-            port_elem.setAttribute(u"portid", unicode(self.port_a.spec[0]))
-            port_elem.setAttribute(u"protocol", self.port_a.spec[1])
+            port_elem = document.createElement("port")
+            port_elem.setAttribute("portid", str(self.port_a.spec[0]))
+            port_elem.setAttribute("protocol", self.port_a.spec[1])
             if self.port_a.state is not None:
-                state_elem = document.createElement(u"state")
-                state_elem.setAttribute(u"state", self.port_a.state)
+                state_elem = document.createElement("state")
+                state_elem.setAttribute("state", self.port_a.state)
                 port_elem.appendChild(state_elem)
             if self.port_a.service == self.port_b.service:
                 port_elem.appendChild(
                         self.port_a.service.to_dom_fragment(document))
             else:
-                a_elem = document.createElement(u"a")
+                a_elem = document.createElement("a")
                 a_elem.appendChild(
                         self.port_a.service.to_dom_fragment(document))
                 port_elem.appendChild(a_elem)
-                b_elem = document.createElement(u"b")
+                b_elem = document.createElement("b")
                 b_elem.appendChild(
                         self.port_b.service.to_dom_fragment(document))
                 port_elem.appendChild(b_elem)
@@ -1026,10 +1023,10 @@ class PortDiff(object):
                 port_elem.appendChild(sr_diff.to_dom_fragment(document))
             portdiff_elem.appendChild(port_elem)
         else:
-            a_elem = document.createElement(u"a")
+            a_elem = document.createElement("a")
             a_elem.appendChild(self.port_a.to_dom_fragment(document))
             portdiff_elem.appendChild(a_elem)
-            b_elem = document.createElement(u"b")
+            b_elem = document.createElement("b")
             b_elem.appendChild(self.port_b.to_dom_fragment(document))
             portdiff_elem.appendChild(b_elem)
 
@@ -1084,13 +1081,13 @@ class ScriptResultDiff(object):
             for op, i1, i2, j1, j2 in diffs.get_opcodes():
                 if op == "replace" or op == "delete":
                     for k in range(i1, i2):
-                        table.append_raw(u"-" + a_lines[k])
+                        table.append_raw("-" + a_lines[k])
                 if op == "replace" or op == "insert":
                     for k in range(j1, j2):
-                        table.append_raw(u"+" + b_lines[k])
+                        table.append_raw("+" + b_lines[k])
                 if op == "equal":
                     for k in range(i1, i2):
-                        table.append_raw(u" " + a_lines[k])
+                        table.append_raw(" " + a_lines[k])
 
     def to_dom_fragment(self, document):
         frag = document.createDocumentFragment()
@@ -1100,11 +1097,11 @@ class ScriptResultDiff(object):
             frag.appendChild(self.sr_a.to_dom_fragment(document))
         else:
             if self.sr_a is not None:
-                a_elem = document.createElement(u"a")
+                a_elem = document.createElement("a")
                 a_elem.appendChild(self.sr_a.to_dom_fragment(document))
                 frag.appendChild(a_elem)
             if self.sr_b is not None:
-                b_elem = document.createElement(u"b")
+                b_elem = document.createElement("b")
                 b_elem.appendChild(self.sr_b.to_dom_fragment(document))
                 frag.appendChild(b_elem)
         return frag
@@ -1118,7 +1115,7 @@ class Table(object):
         copied to the output."""
         self.widths = []
         self.rows = []
-        self.prefix = u""
+        self.prefix = ""
         self.padding = []
         j = 0
         while j < len(template) and template[j] != "*":
@@ -1143,7 +1140,7 @@ class Table(object):
 
         for i in range(len(row)):
             if row[i] is None:
-                s = u""
+                s = ""
             else:
                 s = str(row[i])
             if i == len(self.widths):
@@ -1165,7 +1162,7 @@ class Table(object):
         for row in self.rows:
             parts = [self.prefix]
             i = 0
-            if isinstance(row, basestring):
+            if isinstance(row, str):
                 # A raw string.
                 lines.append(row)
             else:
@@ -1174,13 +1171,13 @@ class Table(object):
                     if i < len(self.padding):
                         parts.append(self.padding[i])
                     i += 1
-                lines.append(u"".join(parts).rstrip())
-        return u"\n".join(lines)
+                lines.append("".join(parts).rstrip())
+        return "\n".join(lines)
 
 
 def warn(str):
     """Print a warning to stderr."""
-    print >> sys.stderr, str
+    print(str, file=sys.stderr)
 
 
 class NmapContentHandler(xml.sax.handler.ContentHandler):
@@ -1200,24 +1197,24 @@ class NmapContentHandler(xml.sax.handler
         self.skip_over = False
 
         self._start_elem_handlers = {
-            u"nmaprun": self._start_nmaprun,
-            u"host": self._start_host,
-            u"hosthint": self._start_hosthint,
-            u"status": self._start_status,
-            u"address": self._start_address,
-            u"hostname": self._start_hostname,
-            u"extraports": self._start_extraports,
-            u"port": self._start_port,
-            u"state": self._start_state,
-            u"service": self._start_service,
-            u"script": self._start_script,
-            u"osmatch": self._start_osmatch,
-            u"finished": self._start_finished,
+            "nmaprun": self._start_nmaprun,
+            "host": self._start_host,
+            "hosthint": self._start_hosthint,
+            "status": self._start_status,
+            "address": self._start_address,
+            "hostname": self._start_hostname,
+            "extraports": self._start_extraports,
+            "port": self._start_port,
+            "state": self._start_state,
+            "service": self._start_service,
+            "script": self._start_script,
+            "osmatch": self._start_osmatch,
+            "finished": self._start_finished,
         }
         self._end_elem_handlers = {
-            u'host': self._end_host,
-            u"hosthint": self._end_hosthint,
-            u'port': self._end_port,
+            'host': self._end_host,
+            "hosthint": self._end_hosthint,
+            'port': self._end_port,
         }
 
     def parent_element(self):
@@ -1247,72 +1244,72 @@ class NmapContentHandler(xml.sax.handler
     def _start_nmaprun(self, name, attrs):
         assert self.parent_element() is None
         if "start" in attrs:
-            start_timestamp = int(attrs.get(u"start"))
+            start_timestamp = int(attrs.get("start"))
             self.scan.start_date = datetime.datetime.fromtimestamp(
                     start_timestamp)
-        self.scan.scanner = attrs.get(u"scanner")
-        self.scan.args = attrs.get(u"args")
-        self.scan.version = attrs.get(u"version")
+        self.scan.scanner = attrs.get("scanner")
+        self.scan.args = attrs.get("args")
+        self.scan.version = attrs.get("version")
 
     def _start_host(self, name, attrs):
-        assert self.parent_element() == u"nmaprun"
+        assert self.parent_element() == "nmaprun"
         self.current_host = Host()
         self.scan.hosts.append(self.current_host)
 
     def _start_hosthint(self, name, attrs):
-        assert self.parent_element() == u"nmaprun"
+        assert self.parent_element() == "nmaprun"
         self.skip_over = True
 
     def _start_status(self, name, attrs):
-        assert self.parent_element() == u"host"
+        assert self.parent_element() == "host"
         assert self.current_host is not None
-        state = attrs.get(u"state")
+        state = attrs.get("state")
         if state is None:
-            warn(u'%s element of host %s is missing the "state" attribute; '
-                    'assuming \unknown\.' % (
+            warn('%s element of host %s is missing the "state" attribute; '
+                    r'assuming \unknown\.' % (
                         name, self.current_host.format_name()))
             return
         self.current_host.state = state
 
     def _start_address(self, name, attrs):
-        assert self.parent_element() == u"host"
+        assert self.parent_element() == "host"
         assert self.current_host is not None
-        addr = attrs.get(u"addr")
+        addr = attrs.get("addr")
         if addr is None:
-            warn(u'%s element of host %s is missing the "addr" '
+            warn('%s element of host %s is missing the "addr" '
                     'attribute; skipping.' % (
                         name, self.current_host.format_name()))
             return
-        addrtype = attrs.get(u"addrtype", u"ipv4")
+        addrtype = attrs.get("addrtype", "ipv4")
         self.current_host.add_address(Address.new(addrtype, addr))
 
     def _start_hostname(self, name, attrs):
-        assert self.parent_element() == u"hostnames"
+        assert self.parent_element() == "hostnames"
         assert self.current_host is not None
-        hostname = attrs.get(u"name")
+        hostname = attrs.get("name")
         if hostname is None:
-            warn(u'%s element of host %s is missing the "name" '
+            warn('%s element of host %s is missing the "name" '
                     'attribute; skipping.' % (
                         name, self.current_host.format_name()))
             return
         self.current_host.add_hostname(hostname)
 
     def _start_extraports(self, name, attrs):
-        assert self.parent_element() == u"ports"
+        assert self.parent_element() == "ports"
         assert self.current_host is not None
-        state = attrs.get(u"state")
+        state = attrs.get("state")
         if state is None:
-            warn(u'%s element of host %s is missing the "state" '
+            warn('%s element of host %s is missing the "state" '
                     'attribute; assuming "unknown".' % (
                         name, self.current_host.format_name()))
             state = None
         if state in self.current_host.extraports:
-            warn(u'Duplicate extraports state "%s" in host %s.' % (
+            warn('Duplicate extraports state "%s" in host %s.' % (
                 state, self.current_host.format_name()))
 
-        count = attrs.get(u"count")
+        count = attrs.get("count")
         if count is None:
-            warn(u'%s element of host %s is missing the "count" '
+            warn('%s element of host %s is missing the "count" '
                     'attribute; assuming 0.' % (
                         name, self.current_host.format_name()))
             count = 0
@@ -1320,99 +1317,99 @@ class NmapContentHandler(xml.sax.handler
             try:
                 count = int(count)
             except ValueError:
-                warn(u"Can't convert extraports count \"%s\" "
+                warn("Can't convert extraports count \"%s\" "
                         "to an integer in host %s; assuming 0." % (
-                            attrs[u"count"], self.current_host.format_name()))
+                            attrs["count"], self.current_host.format_name()))
                 count = 0
         self.current_host.extraports[state] = count
 
     def _start_port(self, name, attrs):
-        assert self.parent_element() == u"ports"
+        assert self.parent_element() == "ports"
         assert self.current_host is not None
-        portid_str = attrs.get(u"portid")
+        portid_str = attrs.get("portid")
         if portid_str is None:
-            warn(u'%s element of host %s missing the "portid" '
+            warn('%s element of host %s missing the "portid" '
                     'attribute; skipping.' % (
                         name, self.current_host.format_name()))
             return
         try:
             portid = int(portid_str)
         except ValueError:
-            warn(u"Can't convert portid \"%s\" to an integer "
+            warn("Can't convert portid \"%s\" to an integer "
                     "in host %s; skipping port." % (
                         portid_str, self.current_host.format_name()))
             return
-        protocol = attrs.get(u"protocol")
+        protocol = attrs.get("protocol")
         if protocol is None:
-            warn(u'%s element of host %s missing the "protocol" '
+            warn('%s element of host %s missing the "protocol" '
                     'attribute; skipping.' % (
                         name, self.current_host.format_name()))
             return
         self.current_port = Port((portid, protocol))
 
     def _start_state(self, name, attrs):
-        assert self.parent_element() == u"port"
+        assert self.parent_element() == "port"
         assert self.current_host is not None
         if self.current_port is None:
             return
         if "state" not in attrs:
-            warn(u'%s element of port %s is missing the "state" '
+            warn('%s element of port %s is missing the "state" '
                     'attribute; assuming "unknown".' % (
                         name, self.current_port.spec_string()))
             return
-        self.current_port.state = attrs[u"state"]
+        self.current_port.state = attrs["state"]
         self.current_host.add_port(self.current_port)
 
     def _start_service(self, name, attrs):
-        assert self.parent_element() == u"port"
+        assert self.parent_element() == "port"
         assert self.current_host is not None
         if self.current_port is None:
             return
-        self.current_port.service.name = attrs.get(u"name")
-        self.current_port.service.product = attrs.get(u"product")
-        self.current_port.service.version = attrs.get(u"version")
-        self.current_port.service.extrainfo = attrs.get(u"extrainfo")
-        self.current_port.service.tunnel = attrs.get(u"tunnel")
+        self.current_port.service.name = attrs.get("name")
+        self.current_port.service.product = attrs.get("product")
+        self.current_port.service.version = attrs.get("version")
+        self.current_port.service.extrainfo = attrs.get("extrainfo")
+        self.current_port.service.tunnel = attrs.get("tunnel")
 
     def _start_script(self, name, attrs):
         result = ScriptResult()
-        result.id = attrs.get(u"id")
+        result.id = attrs.get("id")
         if result.id is None:
-            warn(u'%s element missing the "id" attribute; skipping.' % name)
+            warn('%s element missing the "id" attribute; skipping.' % name)
             return
 
-        result.output = attrs.get(u"output")
+        result.output = attrs.get("output")
         if result.output is None:
-            warn(u'%s element missing the "output" attribute; skipping.'
+            warn('%s element missing the "output" attribute; skipping.'
                     % name)
             return
-        if self.parent_element() == u"prescript":
+        if self.parent_element() == "prescript":
             self.scan.pre_script_results.append(result)
-        elif self.parent_element() == u"postscript":
+        elif self.parent_element() == "postscript":
             self.scan.post_script_results.append(result)
-        elif self.parent_element() == u"hostscript":
+        elif self.parent_element() == "hostscript":
             self.current_host.script_results.append(result)
-        elif self.parent_element() == u"port":
+        elif self.parent_element() == "port":
             self.current_port.script_results.append(result)
         else:
-            warn(u"%s element not inside prescript, postscript, hostscript, "
+            warn("%s element not inside prescript, postscript, hostscript, "
                     "or port element; ignoring." % name)
             return
 
     def _start_osmatch(self, name, attrs):
-        assert self.parent_element() == u"os"
+        assert self.parent_element() == "os"
         assert self.current_host is not None
         if "name" not in attrs:
-            warn(u'%s element of host %s is missing the "name" '
+            warn('%s element of host %s is missing the "name" '
                     'attribute; skipping.' % (
                         name, self.current_host.format_name()))
             return
-        self.current_host.os.append(attrs[u"name"])
+        self.current_host.os.append(attrs["name"])
 
     def _start_finished(self, name, attrs):
-        assert self.parent_element() == u"runstats"
+        assert self.parent_element() == "runstats"
         if "time" in attrs:
-            end_timestamp = int(attrs.get(u"time"))
+            end_timestamp = int(attrs.get("time"))
             self.scan.end_date = datetime.datetime.fromtimestamp(end_timestamp)
 
     def _end_host(self, name):
@@ -1434,23 +1431,23 @@ class XMLWriter (xml.sax.saxutils.XMLGen
 
     def frag(self, frag):
         for node in frag.childNodes:
-            node.writexml(self.f, newl=u"\n")
+            node.writexml(self.f, newl="\n")
 
     def frag_a(self, frag):
-        self.startElement(u"a", {})
+        self.startElement("a", {})
         for node in frag.childNodes:
-            node.writexml(self.f, newl=u"\n")
-        self.endElement(u"a")
+            node.writexml(self.f, newl="\n")
+        self.endElement("a")
 
     def frag_b(self, frag):
-        self.startElement(u"b", {})
+        self.startElement("b", {})
         for node in frag.childNodes:
-            node.writexml(self.f, newl=u"\n")
-        self.endElement(u"b")
+            node.writexml(self.f, newl="\n")
+        self.endElement("b")
 
 
 def usage():
-    print u"""\
+    print("""\
 Usage: %s [option] FILE1 FILE2
 Compare two Nmap XML files and display a list of their differences.
 Differences include host state changes, port state changes, and changes to
@@ -1460,7 +1457,7 @@ service and OS detection.
   -v, --verbose  also show hosts and ports that haven't changed.
   --text         display output in text format (default)
   --xml          display output in XML format\
-""" % sys.argv[0]
+""" % sys.argv[0])
 
 EXIT_EQUAL = 0
 EXIT_DIFFERENT = 1
@@ -1468,8 +1465,8 @@ EXIT_ERROR = 2
 
 
 def usage_error(msg):
-    print >> sys.stderr, u"%s: %s" % (sys.argv[0], msg)
-    print >> sys.stderr, u"Try '%s -h' for help." % sys.argv[0]
+    print("%s: %s" % (sys.argv[0], msg), file=sys.stderr)
+    print("Try '%s -h' for help." % sys.argv[0], file=sys.stderr)
     sys.exit(EXIT_ERROR)
 
 
@@ -1480,7 +1477,7 @@ def main():
     try:
         opts, input_filenames = getopt.gnu_getopt(
                 sys.argv[1:], "hv", ["help", "text", "verbose", "xml"])
-    except getopt.GetoptError, e:
+    except getopt.GetoptError as e:
         usage_error(e.msg)
     for o, a in opts:
         if o == "-h" or o == "--help":
@@ -1490,15 +1487,15 @@ def main():
             verbose = True
         elif o == "--text":
             if output_format is not None and output_format != "text":
-                usage_error(u"contradictory output format options.")
+                usage_error("contradictory output format options.")
             output_format = "text"
         elif o == "--xml":
             if output_format is not None and output_format != "xml":
-                usage_error(u"contradictory output format options.")
+                usage_error("contradictory output format options.")
             output_format = "xml"
 
     if len(input_filenames) != 2:
-        usage_error(u"need exactly two input filenames.")
+        usage_error("need exactly two input filenames.")
 
     if output_format is None:
         output_format = "text"
@@ -1511,8 +1508,8 @@ def main():
         scan_a.load_from_file(filename_a)
         scan_b = Scan()
         scan_b.load_from_file(filename_b)
-    except IOError, e:
-        print >> sys.stderr, u"Can't open file: %s" % str(e)
+    except IOError as e:
+        print("Can't open file: %s" % str(e), file=sys.stderr)
         sys.exit(EXIT_ERROR)
 
     if output_format == "text":
--- a/ndiff/ndifftest.py
+++ b/ndiff/ndifftest.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Unit tests for Ndiff.
 
@@ -22,7 +22,7 @@ for x in dir(ndiff):
 sys.dont_write_bytecode = dont_write_bytecode
 del dont_write_bytecode
 
-import StringIO
+import io
 
 
 class scan_test(unittest.TestCase):
@@ -52,7 +52,7 @@ class scan_test(unittest.TestCase):
         scan.load_from_file("test-scans/single.xml")
         host = scan.hosts[0]
         self.assertEqual(len(host.ports), 5)
-        self.assertEqual(host.extraports.items(), [("filtered", 95)])
+        self.assertEqual(list(host.extraports.items()), [("filtered", 95)])
 
     def test_extraports_multi(self):
         """Test that the correct number of known ports is returned when there
@@ -68,9 +68,9 @@ class scan_test(unittest.TestCase):
         """Test that nmaprun information is recorded."""
         scan = Scan()
         scan.load_from_file("test-scans/empty.xml")
-        self.assertEqual(scan.scanner, u"nmap")
-        self.assertEqual(scan.version, u"4.90RC2")
-        self.assertEqual(scan.args, u"nmap -oX empty.xml -p 1-100")
+        self.assertEqual(scan.scanner, "nmap")
+        self.assertEqual(scan.version, "4.90RC2")
+        self.assertEqual(scan.args, "nmap -oX empty.xml -p 1-100")
 
     def test_addresses(self):
         """Test that addresses are recorded."""
@@ -84,7 +84,7 @@ class scan_test(unittest.TestCase):
         scan = Scan()
         scan.load_from_file("test-scans/simple.xml")
         host = scan.hosts[0]
-        self.assertEqual(host.hostnames, [u"scanme.nmap.org"])
+        self.assertEqual(host.hostnames, ["scanme.nmap.org"])
 
     def test_os(self):
         """Test that OS information is recorded."""
@@ -99,7 +99,7 @@ class scan_test(unittest.TestCase):
         scan.load_from_file("test-scans/complex.xml")
         host = scan.hosts[0]
         self.assertTrue(len(host.script_results) > 0)
-        self.assertTrue(len(host.ports[(22, u"tcp")].script_results) > 0)
+        self.assertTrue(len(host.ports[(22, "tcp")].script_results) > 0)
 
 # This test is commented out because Nmap XML doesn't store any information
 # about down hosts, not even the fact that they are down. Recovering the list
@@ -128,16 +128,16 @@ class host_test(unittest.TestCase):
 
     def test_format_name(self):
         h = Host()
-        self.assertTrue(isinstance(h.format_name(), basestring))
-        h.add_address(IPv4Address(u"127.0.0.1"))
-        self.assertTrue(u"127.0.0.1" in h.format_name())
+        self.assertTrue(isinstance(h.format_name(), str))
+        h.add_address(IPv4Address("127.0.0.1"))
+        self.assertTrue("127.0.0.1" in h.format_name())
         h.add_address(IPv6Address("::1"))
-        self.assertTrue(u"127.0.0.1" in h.format_name())
-        self.assertTrue(u"::1" in h.format_name())
-        h.add_hostname(u"localhost")
-        self.assertTrue(u"127.0.0.1" in h.format_name())
-        self.assertTrue(u"::1" in h.format_name())
-        self.assertTrue(u"localhost" in h.format_name())
+        self.assertTrue("127.0.0.1" in h.format_name())
+        self.assertTrue("::1" in h.format_name())
+        h.add_hostname("localhost")
+        self.assertTrue("127.0.0.1" in h.format_name())
+        self.assertTrue("::1" in h.format_name())
+        self.assertTrue("localhost" in h.format_name())
 
     def test_empty_get_port(self):
         h = Host()
@@ -197,8 +197,8 @@ class host_test(unittest.TestCase):
         h = s.hosts[0]
         self.assertEqual(len(h.ports), 5)
         self.assertEqual(len(h.extraports), 1)
-        self.assertEqual(h.extraports.keys()[0], u"filtered")
-        self.assertEqual(h.extraports.values()[0], 95)
+        self.assertEqual(list(h.extraports.keys())[0], "filtered")
+        self.assertEqual(list(h.extraports.values())[0], 95)
         self.assertEqual(h.state, "up")
 
 
@@ -241,13 +241,13 @@ class port_test(unittest.TestCase):
     """Test the Port class."""
     def test_spec_string(self):
         p = Port((10, "tcp"))
-        self.assertEqual(p.spec_string(), u"10/tcp")
+        self.assertEqual(p.spec_string(), "10/tcp")
         p = Port((100, "ip"))
-        self.assertEqual(p.spec_string(), u"100/ip")
+        self.assertEqual(p.spec_string(), "100/ip")
 
     def test_state_string(self):
         p = Port((10, "tcp"))
-        self.assertEqual(p.state_string(), u"unknown")
+        self.assertEqual(p.state_string(), "unknown")
 
 
 class service_test(unittest.TestCase):
@@ -255,47 +255,47 @@ class service_test(unittest.TestCase):
     def test_compare(self):
         """Test that services with the same contents compare equal."""
         a = Service()
-        a.name = u"ftp"
-        a.product = u"FooBar FTP"
-        a.version = u"1.1.1"
-        a.tunnel = u"ssl"
+        a.name = "ftp"
+        a.product = "FooBar FTP"
+        a.version = "1.1.1"
+        a.tunnel = "ssl"
         self.assertEqual(a, a)
         b = Service()
-        b.name = u"ftp"
-        b.product = u"FooBar FTP"
-        b.version = u"1.1.1"
-        b.tunnel = u"ssl"
+        b.name = "ftp"
+        b.product = "FooBar FTP"
+        b.version = "1.1.1"
+        b.tunnel = "ssl"
         self.assertEqual(a, b)
-        b.name = u"http"
+        b.name = "http"
         self.assertNotEqual(a, b)
         c = Service()
         self.assertNotEqual(a, c)
 
     def test_tunnel(self):
         serv = Service()
-        serv.name = u"http"
-        serv.tunnel = u"ssl"
-        self.assertEqual(serv.name_string(), u"ssl/http")
+        serv.name = "http"
+        serv.tunnel = "ssl"
+        self.assertEqual(serv.name_string(), "ssl/http")
 
     def test_version_string(self):
         serv = Service()
-        serv.product = u"FooBar"
+        serv.product = "FooBar"
         self.assertTrue(len(serv.version_string()) > 0)
         serv = Service()
-        serv.version = u"1.2.3"
+        serv.version = "1.2.3"
         self.assertTrue(len(serv.version_string()) > 0)
         serv = Service()
-        serv.extrainfo = u"misconfigured"
+        serv.extrainfo = "misconfigured"
         self.assertTrue(len(serv.version_string()) > 0)
         serv = Service()
-        serv.product = u"FooBar"
-        serv.version = u"1.2.3"
+        serv.product = "FooBar"
+        serv.version = "1.2.3"
         # Must match Nmap output.
         self.assertEqual(serv.version_string(),
-                u"%s %s" % (serv.product, serv.version))
-        serv.extrainfo = u"misconfigured"
+                "%s %s" % (serv.product, serv.version))
+        serv.extrainfo = "misconfigured"
         self.assertEqual(serv.version_string(),
-                u"%s %s (%s)" % (serv.product, serv.version, serv.extrainfo))
+                "%s %s (%s)" % (serv.product, serv.version, serv.extrainfo))
 
 
 class ScanDiffSub(ScanDiff):
@@ -703,7 +703,7 @@ class scan_diff_xml_test(unittest.TestCa
         a.load_from_file("test-scans/empty.xml")
         b = Scan()
         b.load_from_file("test-scans/simple.xml")
-        f = StringIO.StringIO()
+        f = io.StringIO()
         self.scan_diff = ScanDiffXML(a, b, f)
         self.scan_diff.output()
         self.xml = f.getvalue()
@@ -712,8 +712,8 @@ class scan_diff_xml_test(unittest.TestCa
     def test_well_formed(self):
         try:
             document = xml.dom.minidom.parseString(self.xml)
-        except Exception, e:
-            self.fail(u"Parsing XML diff output caused the exception: %s"
+        except Exception as e:
+            self.fail("Parsing XML diff output caused the exception: %s"
                     % str(e))
 
 
@@ -739,8 +739,8 @@ def host_apply_diff(host, diff):
         host.os = diff.host_b.os[:]
 
     if diff.extraports_changed:
-        for state in host.extraports.keys():
-            for port in host.ports.values():
+        for state in list(host.extraports.keys()):
+            for port in list(host.ports.values()):
                 if port.state == state:
                     del host.ports[port.spec]
         host.extraports = diff.host_b.extraports.copy()
--- a/ndiff/scripts/ndiff
+++ b/ndiff/scripts/ndiff
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Ndiff
 #
@@ -66,15 +66,15 @@ if INSTALL_LIB is not None and is_secure
 
 try:
     import ndiff
-except ImportError, e:
-    print >> sys.stderr, """\
+except ImportError as e:
+    print("""\
 Could not import the ndiff module: %s.
-I checked in these directories:""" % repr(e.message)
+I checked in these directories:""" % repr(e), file=sys.stderr)
     for dir in sys.path:
-        print >> sys.stderr, "    %s" % dir
-    print >> sys.stderr, """\
+        print("    %s" % dir, file=sys.stderr)
+    print("""\
 If you installed Ndiff in another directory, you may have to add the
-modules directory to the PYTHONPATH environment variable."""
+modules directory to the PYTHONPATH environment variable.""", file=sys.stderr)
     sys.exit(1)
 
 import ndiff
--- a/ndiff/setup.py
+++ b/ndiff/setup.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import errno
 import sys
@@ -94,7 +94,7 @@ class checked_install(distutils.command.
         self.saved_prefix = sys.prefix
         try:
             distutils.command.install.install.finalize_options(self)
-        except distutils.errors.DistutilsPlatformError, e:
+        except distutils.errors.DistutilsPlatformError as e:
             raise distutils.errors.DistutilsPlatformError(str(e) + """
 Installing your distribution's python-dev package may solve this problem.""")
 
@@ -152,16 +152,16 @@ Installing your distribution's python-de
                 self.install_scripts, "uninstall_" + APP_NAME)
 
         uninstaller = """\
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import errno, os, os.path, sys
 
-print 'Uninstall %(name)s'
+print('Uninstall %(name)s')
 
 answer = raw_input('Are you sure that you want to uninstall '
     '%(name)s (yes/no) ')
 
 if answer != 'yes' and answer != 'y':
-    print 'Not uninstalling.'
+    print('Not uninstalling.')
     sys.exit(0)
 
 """ % {'name': APP_NAME}
@@ -177,8 +177,8 @@ if answer != 'yes' and answer != 'y':
                     # This should never happen (everything gets installed
                     # inside the root), but if it does, be safe and don't
                     # delete anything.
-                    uninstaller += ("print '%s was not installed inside "
-                        "the root %s; skipping.'\n" % (output, self.root))
+                    uninstaller += ("print('%s was not installed inside "
+                        "the root %s; skipping.')\n" % (output, self.root))
                     continue
                 output = path_strip_prefix(output, self.root)
                 assert os.path.isabs(output)
@@ -202,24 +202,24 @@ for path in INSTALLED_FILES:
         dirs.append(path)
 # Delete the files.
 for file in files:
-    print "Removing '%s'." % file
+    print("Removing '%s'." % file)
     try:
         os.remove(file)
-    except OSError, e:
-        print >> sys.stderr, '  Error: %s.' % str(e)
+    except OSError as e:
+        print('  Error: %s.' % str(e), file=sys.stderr)
 # Delete the directories. First reverse-sort the normalized paths by
 # length so that child directories are deleted before their parents.
 dirs = [os.path.normpath(dir) for dir in dirs]
 dirs.sort(key = len, reverse = True)
 for dir in dirs:
     try:
-        print "Removing the directory '%s'." % dir
+        print("Removing the directory '%s'." % dir)
         os.rmdir(dir)
-    except OSError, e:
+    except OSError as e:
         if e.errno == errno.ENOTEMPTY:
-            print "Directory '%s' not empty; not removing." % dir
+            print("Directory '%s' not empty; not removing." % dir)
         else:
-            print >> sys.stderr, str(e)
+            print(str(e), file=sys.stderr)
 """
 
         uninstaller_file = open(uninstaller_filename, 'w')
@@ -227,7 +227,7 @@ for dir in dirs:
         uninstaller_file.close()
 
         # Set exec bit for uninstaller
-        mode = ((os.stat(uninstaller_filename)[ST_MODE]) | 0555) & 07777
+        mode = ((os.stat(uninstaller_filename)[ST_MODE]) | 0o555) & 0o7777
         os.chmod(uninstaller_filename, mode)
 
     def write_installed_files(self):
@@ -241,7 +241,7 @@ for dir in dirs:
         with open(INSTALLED_FILES_NAME, "w") as f:
             for output in self.get_installed_files():
                 assert "\n" not in output
-                print >> f, output
+                print(output, file=f)
 
 
 class my_uninstall(distutils.cmd.Command):
@@ -263,7 +263,7 @@ class my_uninstall(distutils.cmd.Command
         # Read the list of installed files.
         try:
             f = open(INSTALLED_FILES_NAME, "r")
-        except IOError, e:
+        except IOError as e:
             if e.errno == errno.ENOENT:
                 log.error("Couldn't open the installation record '%s'. "
                         "Have you installed yet?" % INSTALLED_FILES_NAME)
@@ -286,7 +286,7 @@ class my_uninstall(distutils.cmd.Command
             try:
                 if not self.dry_run:
                     os.remove(file)
-            except OSError, e:
+            except OSError as e:
                 log.error(str(e))
         # Delete the directories. First reverse-sort the normalized paths by
         # length so that child directories are deleted before their parents.
@@ -297,16 +297,16 @@ class my_uninstall(distutils.cmd.Command
                 log.info("Removing the directory '%s'." % dir)
                 if not self.dry_run:
                     os.rmdir(dir)
-            except OSError, e:
+            except OSError as e:
                 if e.errno == errno.ENOTEMPTY:
                     log.info("Directory '%s' not empty; not removing." % dir)
                 else:
                     log.error(str(e))
 
 
-distutils.core.setup(name=u"ndiff", scripts=[u"scripts/ndiff"],
-    py_modules=[u"ndiff"],
-    data_files=[(u"share/man/man1", [u"docs/ndiff.1"])],
+distutils.core.setup(name="ndiff", scripts=["scripts/ndiff"],
+    py_modules=["ndiff"],
+    data_files=[("share/man/man1", ["docs/ndiff.1"])],
     cmdclass={
         "install_egg_info": null_command,
         "install": checked_install,
--- a/ndiff/test-scans/anonymize.py
+++ b/ndiff/test-scans/anonymize.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Anonymize an Nmap XML file, replacing host name and IP addresses with random
 # anonymous ones. Anonymized names will be consistent between runs of the
@@ -20,20 +20,20 @@ r = random.Random()
 
 
 def hash(s):
-    digest = hashlib.sha512(s).hexdigest()
+    digest = hashlib.sha512(s.encode()).hexdigest()
     return int(digest, 16)
 
 
 def anonymize_mac_address(addr):
     r.seed(hash(addr))
     nums = (0, 0, 0) + tuple(r.randrange(256) for i in range(3))
-    return u":".join(u"%02X" % x for x in nums)
+    return ":".join("%02X" % x for x in nums)
 
 
 def anonymize_ipv4_address(addr):
     r.seed(hash(addr))
     nums = (10,) + tuple(r.randrange(256) for i in range(3))
-    return u".".join(unicode(x) for x in nums)
+    return ".".join(str(x) for x in nums)
 
 
 def anonymize_ipv6_address(addr):
@@ -41,7 +41,7 @@ def anonymize_ipv6_address(addr):
     # RFC 4193.
     nums = (0xFD00 + r.randrange(256),)
     nums = nums + tuple(r.randrange(65536) for i in range(7))
-    return u":".join("%04X" % x for x in nums)
+    return ":".join("%04X" % x for x in nums)
 
 # Maps to memoize address and host name conversions.
 hostname_map = {}
@@ -54,11 +54,11 @@ def anonymize_hostname(name):
     LETTERS = "acbdefghijklmnopqrstuvwxyz"
     r.seed(hash(name))
     length = r.randrange(5, 10)
-    prefix = u"".join(r.sample(LETTERS, length))
+    prefix = "".join(r.sample(LETTERS, length))
     num = r.randrange(1000)
-    hostname_map[name] = u"%s-%d.example.com" % (prefix, num)
+    hostname_map[name] = "%s-%d.example.com" % (prefix, num)
     if VERBOSE:
-        print >> sys.stderr, "Replace %s with %s" % (name, hostname_map[name])
+        print("Replace %s with %s" % (name, hostname_map[name]), file=sys.stderr)
     return hostname_map[name]
 
 mac_re = re.compile(r'\b([0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2}\b')
@@ -78,7 +78,7 @@ def anonymize_address(addr):
     else:
         assert False
     if VERBOSE:
-        print >> sys.stderr, "Replace %s with %s" % (addr, address_map[addr])
+        print("Replace %s with %s" % (addr, address_map[addr]), file=sys.stderr)
     return address_map[addr]
 
 
